Current collector shoe



l Feb. 22, 1944. ,1 R PALMER v 2,342,296

CURRENT COLLECTOR SHOE Filed My 17. 194s I Jnnentor JAY R. PALMER Patented Feb. 22, 1944 CURRENT COLLECTOR SHOE .lay Rf. Palmer, Mansfield, Ohio, assigner to The Ohio Brass Company, Mansfield, Ohio, `a corporation of New Jersey Application May 17, 1943, Serial No. 487,389

l0 Claims.

My invention relatesto current collector shoes and particularly to removable inserts therefor.

The shoe comprises a removable insert of oonductive material, preferably non-metallic, held in a metal frame adapted to be mounted on a support at the upper end of a trolley pole.

A shoe and insert of the type I refer to is shown `in U. S. Patent 2,185,257 issued January 2, 1940, but I am not claiming broadly such combination.

Experience shows that shoes and inserts as set forth in the above patent, under some conditions of operation form a narrow groove for the trolley wire as the 'insert wears away, in place oi forming a wider groove suiicient to include the lips of the support for the wire or other overhead ittings such as frogs, crossings, etc.

rIhis narrow grooving of the insert is due to the wear of the inserts being due largely to the trolley wire which may constitute 90% of the engagement between the insert and the overhead construction. The result is that under some conditions the insert groove wears to substantially the diameter of the wire and therefore when the insert passes an ear or other overhead tting the groove is vtoo narrow `to properly include the tting.

The result is that there is a Wedging action vupon the insert which will often break `the sides forming the groove and such vbreakage ymay be at most any point or points of the insert which is preferably of carbon, graphite or a mixture of carbon and metal or carbon impregnated with metal after forming.

The object of my invention is lto provide the insert with means whereby the point or points of breakage may be controlled or predetermined.

My invention resides in the new and useful construction, combination and Vrelation of the parts hereinafter described and shown inv the accompanying drawing.

In the drawing:

Fig. 1 is a side View in elevation and partial section of my invention.

Fig. 2 is an end view in partial section of Fig. 1.

Fig. 3 is a top view of Fig. 1.

Figs. 4 and 5 are top and side views respectively of the insert referred `to above.

Fig. 6 is an enlarged end view of Figs. fi and 5.

In the preferred embodiment o1" my invention I provide a frame I of metal` which may be of one piece as per the above patent or it may be of two pieces split longitudinally as shown in U. S. Patent-2,185,268 issuedrJanuary 2,1940. lAsishown in Figs. 2 and y3 herein the frame is split diagonally at one end and the opening between the flanges or side walls 2 at the end adjusted by the screw 3 whereby the insert 4 may be held in position.

The slot formed by the flanges 2 and the end walls is open at the top and bottom whereby the insert 4 is positioned in the frame by passing it through the bottom opening until it engages the longitudinal shoulders 5, in which case the lower face of the insert will be substantially flush with the lower longitudinal edges of the flanges 2.

The end walls are relatively heavy and low as compared with the side walls and the upper faces 6 and 'l thereof limit the maximum depth to which the insert should be worn.

One end of the frame I is provided with a hook member 8 and the other end with a threaded lug S to receive an attaching bolt, by means of which the frame is secured to a support (not shown).

I prefer to provide the upper face of the insert when new with a rather narrow and shallow groove l0, suflicient however to center the trolley wire with respect to the insert and frame and still leave a maximum amount of insert for wear.

In the use of the terms upper face and lower face I refer to the same as applied to the device as in normal use or service.

In service, as already pointed out, the groove IE] as it increases in depth may not increase much in width or even much greater than the diameter of the trolley wire as shown by a in Fig. 6, in which case poor operation may result.

However if as the groove lil wears deeper it also increases in width from its original, as shown by b in Fig. 6, then when the shoe comes to a sup porting ear in which the lips substantially encircle the wire or to va frog or crossing, the shoe will pass these points without jumping or dewiring,

In order to ease the situation where the groove wears narrow and the Wedging pressure on the side walls is considerable and the pounding on the insert severe, I provide a longitudinal groove l l `preferably on each of the side faces oi the insert, andlocate the groove somewhere between the point of maximum depth of the groove as represented by the .transverse-longitudinal plane x-y and the upper face of the insert.

If the groove I0 wears too narrow the pressure against the side walls of the insert cause the walls to break along the `grooves li (see Fig. G) and the part above the grooves H will crumble laway thereby relieving the insert of stress and automatically producing new Aand improved operating conditions.

U. S. kPatent 2,185,268 referred to above kshows longitudinal grooves in :the side faces of the insert. These grooves however are for the purpose of interlocking with projections on the face to prevent inadvertent removal through the bottom of the frame. The grooves are located below maximum wear point (plane :c-g/ of my disclosure) therefore the grooves of the patent will not function in the manner I have described for the grooves l l, in fact the grooves in the said patent do not materially affect the strength of the insert as they are always in the solid portion of the insert. The grooves of the patent will not affect the portion of the insertl within the wear portion (above the plane :r-y of my dis closure).

I may make the grooves Il dentate in place or crenate in form in which case the side walls will be more sensitive to pressure and break more readily.

It will be evident that the grooves H in order to function as I have described must be located above the plane :c4-y and the location within the wear portion of the insert may be varied to meet conditions as required by equal operating conditions.

rhe grooves lll and I I may be produced in the walls of the insert at the time of forming the insert or may be easily applied after forming a blank insert as by a Carborundum wheel of proper shape.

By shaping the surface of the side walls of the insert as shown in Fig. 4, it has been found to resist breakage of the insert and also tends to center the insert longitudinally in the holder.

lThis may be a disadvantage in cases where the groove lll wears narrow as pointed out above, but by the application of the groove Il to the side walls as above described or other satisfactory means, the insert may be relieved of its resistance to breakage and caused to break at a predetermined point to certain local operating conditions as above set forth. Therefore the insert with the side grooves Il will meet certain operating conditions better than the insert without the grooves Il and it is optional with the operators of a trolley system as to which form of insert is used.

It will be evident to those skilled in the art that I may use a plurality of grooves l l, probably not more than two, on one or each side of the insert. This permits of a progressive breakdown of the side walls of the insert in place of a single break-down.

Besides causing a jumping of the current collector' and a possible dewirement, a narrow groove tends to wear away the fittings of the overhead system'much more rapidly than a wide groove.

The groove or grooves Il must however be located within that portion of the insert subject to wear as for instance above the end walls of the holder and preferably about midway between the plane x-y and the upper face of the insert.

Having described my invention I claim:

l. In a current collector comprising a metal holder having side and end walls, the side walls being higher than the end walls and an elongated carbon insert positioned between said walls, thev combination with the insert of means to reduce the strength of the insert at a point between the upper face of said end walls and the upper face of the insert. f v

2. In a current collector comprising a metal holder having side and end Walls, the side wall being higher than the end walls and an elongated insert of frangible current conducting material positioned between said walls, the combination with the insert of means to reduce the strength of the insert at a point between the upper surface of said end walls and the upper face of the insert.

3. An insert for a current collector shoe comprising an elongated body of frangible current conducting material varying in width between its side faces, longitudinally disposed means along one or both side faces positioned nearer to the upper face of the insert than to the lower face thereof whereby the resistance of the side walls of the insert to breakage along said means is reduced as and for the purpose described.

4. An yinsert for a current collector shoe comprising an elongated body of frangible current conducting material and longitudinally disposed means along one or both side faces between the upper face of the insert and a transverse-longitudinal plane through the point of maximum allowable wear of the insert to reduce the re sistance of the side walls to breakage along said means for the purpose described.

5. In a current collector comprising a metal holder having side walls and end walls, the end walls being lower in height than the side walls and an insert of frangible current conducting material positioned between said walls," the combination with the insert at points between the upper face of the insert and a transverse-longitudinal plane through the point of maximum wear of the insert of means to reduce the otherwise normal strength of the insert at the position of the said means.

6. A current collector comprising in combination a metal holder having relatively higher side walls than end walls and forming an elongated open top and open bottom slot, an insert of frangible current conducting material positioned in said slot, a shallow longitudinal groove in the' upper face of the insert adapted to become deeper as the material of the insert wears away and means associated with that portion of the insert above the upper face of the said end walls to reduce the strength of the insert at a predetermined point thereof whereby the insert Walls will break away under adverse operating conditions.

'7. An insert for a current collector shoe comprising an elongated body of frangible current conducting material and longitudinally disposed means associated with that portion of the body positioned between the upper face of the insert and a transverse-longitudinal plane through the point of maximum allowable wear of the insert to effect a localized reduction in the strength of the insert above said plane.

8. An insert for a current collector comprising an elongated frangible current conducting body comprising a carbonaceous material and a metal lic powder uniformly intermixed and longitudinally disposed means associated with that portion of the body positioned between the upper face of the insert and a transverse-longitudinal plane through the point of lower maximum allowable wear of the insert to reduce its strength.

9. An insert for a current collector comprising an elongated body of frangible current conducting material adapted to wear away from friction with parts of an over-head trolley system and form a longitudinal groove of increasing depth forthe trolley wire and its fitting and means associated with that portion of the body subject to allowable wear toefect a breakage of the side walls forming the groove providing the groove tends to wear too narrow for said Wire fittings.

10. 1n a current collector for overhead trolley systems comprising a metal holder with upstanding side Walls and lower end Walls forming an open top and bottom slot and an insert of carbonaceous material impregnated with a metal, the combination with the insert of means associate with the insert and positioned above the upper faces of the end walls to reduce the resistance to breakage at a predetermineri point of the insert.

JAY R. PALMER. 

